我必须用三角形画出我的名字。我了解如何处理着色器。我只是对如何实际绘制对象并将其连接以形成字母感到困惑。
我已经获得了一些可以使用的代码:
#include "Angel.h"
const int NumPoints = 50000;
/*This function initializes an array of 3d vectors
and sends it to the graphics card along with shaders
properly connected to them.*/
void
init( void )
{
vec3 points[NumPoints];
// Specifiy the vertices for a triangle
vec3 vertices[] = {
vec3( -1.0, -1.0, 0.0 ),
vec3( 0.0, 1.0, 0.0 ),
vec3( 1.0, -1.0, 0.0 )
};
// Select an arbitrary initial point inside of the triangle
points[0] = vec3( 0.0, 1.0, 0.0 );
// compute and store NumPoints - 1 new points
for ( int i = 1; i < NumPoints; ++i ) {
int j = rand() % 3; // pick a vertex from the triangle at random
// Compute the point halfway between the selected vertex
// and the previous point
points[i] = ( points[i - 1] + vertices[j] ) / 2.0;
}
// Create a vertex array object
GLuint vao; //just an integer recognized by graphics card
glGenVertexArrays( 1, &vao ); //generate 1 buffer
glBindVertexArray( vao ); //become array buffer
// Create and initialize a buffer object //sends it to graphics card
GLuint buffer;
glGenBuffers( 1, &buffer );
glBindBuffer( GL_ARRAY_BUFFER, buffer );
glBufferData( GL_ARRAY_BUFFER, sizeof(points), points, GL_STATIC_DRAW ); //size of array glstatic draw means this point isnt gonna change its static
// Load shaders and use the resulting shader program
GLuint program = InitShader("simpleShader - Copy.vert", "simpleShader - Copy.frag");
// make these shaders the current shaders
glUseProgram( program );
// Initialize the vertex position attribute from the vertex shader
GLuint loc = glGetAttribLocation( program, "vPosition" ); //find the location in the code
glEnableVertexAttribArray( loc );
glVertexAttribPointer( loc, 3, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0) );
glClearColor( 0.5, 0.5, 0.5, 1.0 ); // gray background
}
//----------------------------------------------------------------------------
/* This function handles the display and it is automatically called by GLUT
once it is declared as the display function. The application should not
call it directly.
*/
void
display( void )
{
glClear( GL_COLOR_BUFFER_BIT ); // clear the window
glDrawArrays( GL_POINTS, 0, NumPoints ); // draw the points
glFlush(); // flush the buffer
}
//----------------------------------------------------------------------------
/* This function handles the keyboard and it is called by GLUT once it is
declared as the keyboard function. The application should not call it
directly.
*/
void
keyboard( unsigned char key, int x, int y )
{
switch ( key ) {
case 033: // escape key
exit( EXIT_SUCCESS ); // terminates the program
break;
}
}
//----------------------------------------------------------------------------
/* This is the main function that calls all the functions to initialize
and setup the OpenGL environment through GLUT and GLEW.
*/
int
main( int argc, char **argv )
{
// Initialize GLUT
glutInit( &argc, argv );
// Initialize the display mode to a buffer with Red, Green, Blue and Alpha channels
glutInitDisplayMode( GLUT_RGBA );
// Set the window size
glutInitWindowSize( 512, 512 );
// Here you set the OpenGL version
glutInitContextVersion( 3, 2 );
//Use only one of the next two lines
//glutInitContextProfile( GLUT_CORE_PROFILE );
glutInitContextProfile( GLUT_COMPATIBILITY_PROFILE );
glutCreateWindow( "Simple GLSL example" );
// Uncomment if you are using GLEW
glewInit();
// initialize the array and send it to the graphics card
init();
// provide the function that handles the display
glutDisplayFunc( display );
// provide the functions that handles the keyboard
glutKeyboardFunc( keyboard );
glutMainLoop();
return 0;
}
答案 0 :(得分:2)
您的问题似乎旨在使您熟悉设置和使用顶点缓冲区。如果是这样,那么如何得出三角形都没关系-关键是要了解设置的工作原理。
因此,您要做的第一件事是阅读有关此主题的教科书。如果没有文本,则需要在OpenGL参考中查找图形调用。
如果按原样运行程序,它应该绘制一堆随机选择的,断开的点(以分形的形式,但仍然...)。这是因为实际的绘制调用glDrawArrays()
是用枚举值GL_POINTS
调用的,该值告诉它绘制点作为第一个参数。
如果您阅读glDrawArrays()
的文档,它应该列出该参数的其他值,其中一些以各种方式绘制三角形。其中最直接的方法是GL_TRIANGLES
,但我建议您查找所有这些内容,以使您了解选择的内容。
生成三角形由您决定。如果您的名字很短,手工生成它们应该很容易。注意,您应该完全替换生成随机点的代码。选项包括: